The urgency of removing organic contaminants from subsurface formations has become increasingly more apparent during the last three decades. This urgency has spawned a tremendous effort to improve subsurface decontamination techniques.
Subsurface decontamination techniques fall into one of two broad classes, aboveground methods and in situ methods. Above-ground methods generally require the removal of contaminated soil and water from the subsurface formation, treatment of such soil and water in aboveground facilities, and re-introduction of the decontaminated water and soil into the subsurface formation. Above-ground methods have been found to be effective but extremely expensive, especially where the subsurface contamination is wide-spread.
For this reason, in situ methods are preferred wherever possible. In almost all in situ methods, contaminated liquids and vapors are withdrawn from a contaminated zone within the subsurface formation via one or more extraction wells. Typically, the contaminated liquids are pumped from the bottom of the extraction well, and the contaminated vapors are removed from the extraction well under vacuum. After removal from the extraction well, these two fluid streams (contaminated liquids and contaminated vapors) are typically treated in separate treatment facilities.
One problem experienced with such in situ processes arises from the large capital and operating expenses of the separate treatment facilities for the contaminated vapor and contaminated liquid streams.
Accordingly, there is a need for an in situ subsurface decontamination method wherein the costs of treating the extracted contaminated vapor and contaminated liquid streams are minimized.